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forgejo/vendor/gopkg.in/alexcesaro/quotedprintable.v3/encodedword.go
Thomas Boerger b6a95a8cb3 Integrate public as bindata optionally (#293)
* Dropped unused codekit config

* Integrated dynamic and static bindata for public

* Ignore public bindata

* Add a general generate make task

* Integrated flexible public assets into web command

* Updated vendoring, added all missiong govendor deps

* Made the linter happy with the bindata and dynamic code

* Moved public bindata definition to modules directory

* Ignoring the new bindata path now

* Updated to the new public modules import path

* Updated public bindata command and drop the new prefix
2016-11-30 00:26:36 +08:00

279 lines
6.2 KiB
Go
Vendored

package quotedprintable
import (
"bytes"
"encoding/base64"
"errors"
"fmt"
"io"
"strings"
"unicode"
"unicode/utf8"
)
// A WordEncoder is a RFC 2047 encoded-word encoder.
type WordEncoder byte
const (
// BEncoding represents Base64 encoding scheme as defined by RFC 2045.
BEncoding = WordEncoder('b')
// QEncoding represents the Q-encoding scheme as defined by RFC 2047.
QEncoding = WordEncoder('q')
)
var (
errInvalidWord = errors.New("mime: invalid RFC 2047 encoded-word")
)
// Encode returns the encoded-word form of s. If s is ASCII without special
// characters, it is returned unchanged. The provided charset is the IANA
// charset name of s. It is case insensitive.
func (e WordEncoder) Encode(charset, s string) string {
if !needsEncoding(s) {
return s
}
return e.encodeWord(charset, s)
}
func needsEncoding(s string) bool {
for _, b := range s {
if (b < ' ' || b > '~') && b != '\t' {
return true
}
}
return false
}
// encodeWord encodes a string into an encoded-word.
func (e WordEncoder) encodeWord(charset, s string) string {
buf := getBuffer()
defer putBuffer(buf)
buf.WriteString("=?")
buf.WriteString(charset)
buf.WriteByte('?')
buf.WriteByte(byte(e))
buf.WriteByte('?')
if e == BEncoding {
w := base64.NewEncoder(base64.StdEncoding, buf)
io.WriteString(w, s)
w.Close()
} else {
enc := make([]byte, 3)
for i := 0; i < len(s); i++ {
b := s[i]
switch {
case b == ' ':
buf.WriteByte('_')
case b <= '~' && b >= '!' && b != '=' && b != '?' && b != '_':
buf.WriteByte(b)
default:
enc[0] = '='
enc[1] = upperhex[b>>4]
enc[2] = upperhex[b&0x0f]
buf.Write(enc)
}
}
}
buf.WriteString("?=")
return buf.String()
}
const upperhex = "0123456789ABCDEF"
// A WordDecoder decodes MIME headers containing RFC 2047 encoded-words.
type WordDecoder struct {
// CharsetReader, if non-nil, defines a function to generate
// charset-conversion readers, converting from the provided
// charset into UTF-8.
// Charsets are always lower-case. utf-8, iso-8859-1 and us-ascii charsets
// are handled by default.
// One of the the CharsetReader's result values must be non-nil.
CharsetReader func(charset string, input io.Reader) (io.Reader, error)
}
// Decode decodes an encoded-word. If word is not a valid RFC 2047 encoded-word,
// word is returned unchanged.
func (d *WordDecoder) Decode(word string) (string, error) {
fields := strings.Split(word, "?") // TODO: remove allocation?
if len(fields) != 5 || fields[0] != "=" || fields[4] != "=" || len(fields[2]) != 1 {
return "", errInvalidWord
}
content, err := decode(fields[2][0], fields[3])
if err != nil {
return "", err
}
buf := getBuffer()
defer putBuffer(buf)
if err := d.convert(buf, fields[1], content); err != nil {
return "", err
}
return buf.String(), nil
}
// DecodeHeader decodes all encoded-words of the given string. It returns an
// error if and only if CharsetReader of d returns an error.
func (d *WordDecoder) DecodeHeader(header string) (string, error) {
// If there is no encoded-word, returns before creating a buffer.
i := strings.Index(header, "=?")
if i == -1 {
return header, nil
}
buf := getBuffer()
defer putBuffer(buf)
buf.WriteString(header[:i])
header = header[i:]
betweenWords := false
for {
start := strings.Index(header, "=?")
if start == -1 {
break
}
cur := start + len("=?")
i := strings.Index(header[cur:], "?")
if i == -1 {
break
}
charset := header[cur : cur+i]
cur += i + len("?")
if len(header) < cur+len("Q??=") {
break
}
encoding := header[cur]
cur++
if header[cur] != '?' {
break
}
cur++
j := strings.Index(header[cur:], "?=")
if j == -1 {
break
}
text := header[cur : cur+j]
end := cur + j + len("?=")
content, err := decode(encoding, text)
if err != nil {
betweenWords = false
buf.WriteString(header[:start+2])
header = header[start+2:]
continue
}
// Write characters before the encoded-word. White-space and newline
// characters separating two encoded-words must be deleted.
if start > 0 && (!betweenWords || hasNonWhitespace(header[:start])) {
buf.WriteString(header[:start])
}
if err := d.convert(buf, charset, content); err != nil {
return "", err
}
header = header[end:]
betweenWords = true
}
if len(header) > 0 {
buf.WriteString(header)
}
return buf.String(), nil
}
func decode(encoding byte, text string) ([]byte, error) {
switch encoding {
case 'B', 'b':
return base64.StdEncoding.DecodeString(text)
case 'Q', 'q':
return qDecode(text)
}
return nil, errInvalidWord
}
func (d *WordDecoder) convert(buf *bytes.Buffer, charset string, content []byte) error {
switch {
case strings.EqualFold("utf-8", charset):
buf.Write(content)
case strings.EqualFold("iso-8859-1", charset):
for _, c := range content {
buf.WriteRune(rune(c))
}
case strings.EqualFold("us-ascii", charset):
for _, c := range content {
if c >= utf8.RuneSelf {
buf.WriteRune(unicode.ReplacementChar)
} else {
buf.WriteByte(c)
}
}
default:
if d.CharsetReader == nil {
return fmt.Errorf("mime: unhandled charset %q", charset)
}
r, err := d.CharsetReader(strings.ToLower(charset), bytes.NewReader(content))
if err != nil {
return err
}
if _, err = buf.ReadFrom(r); err != nil {
return err
}
}
return nil
}
// hasNonWhitespace reports whether s (assumed to be ASCII) contains at least
// one byte of non-whitespace.
func hasNonWhitespace(s string) bool {
for _, b := range s {
switch b {
// Encoded-words can only be separated by linear white spaces which does
// not include vertical tabs (\v).
case ' ', '\t', '\n', '\r':
default:
return true
}
}
return false
}
// qDecode decodes a Q encoded string.
func qDecode(s string) ([]byte, error) {
dec := make([]byte, len(s))
n := 0
for i := 0; i < len(s); i++ {
switch c := s[i]; {
case c == '_':
dec[n] = ' '
case c == '=':
if i+2 >= len(s) {
return nil, errInvalidWord
}
b, err := readHexByte(s[i+1], s[i+2])
if err != nil {
return nil, err
}
dec[n] = b
i += 2
case (c <= '~' && c >= ' ') || c == '\n' || c == '\r' || c == '\t':
dec[n] = c
default:
return nil, errInvalidWord
}
n++
}
return dec[:n], nil
}